Hitby refactor (#19624)

Refactored hitby to be in line with TG's version.
Refactored item weight defines to a more clear naming scheme, also in
line with TG's version.
Refactored how the movement bumps are handled, ported signals to handle
them, in preparation for the movement update.
Fixed disposal hit bouncing the hitting atom on the wall.
Items do not push other items anymore if they are tiny.

code/modules/spell_system/artifacts/items/lich_phylactery.dm

@@ -4,7 +4,7 @@
 	icon = 'icons/obj/wizard.dmi'
 	icon_state = "cursedheart-off"
 	origin_tech = list(TECH_BLUESPACE = 8, TECH_MATERIAL = 8, TECH_BIO = 8)
-	w_class = ITEMSIZE_HUGE
+	w_class = WEIGHT_CLASS_HUGE
 	light_color = "#6633CC"
 	light_power = 3
 	light_range = 4

code/modules/spell_system/artifacts/items/poppet.dm

@@ -4,7 +4,7 @@
 	desc = "A rustic doll with a vague humanoid shape."
 	icon = 'icons/obj/wizard.dmi'
 	icon_state = "poppet"
-	w_class = ITEMSIZE_SMALL
+	w_class = WEIGHT_CLASS_SMALL
 	var/datum/weakref/target = null
 	var/countenance = null //what species does it looks like?
 	var/cooldown_time = 120